This invention relates to a system and a method for monitoring the loading of a diesel particulate filter, and more particularly, to a system and method for accurately monitoring the loading of a diesel particulate filter which does not require the use of pressure and temperature sensors within the vehicle""s exhaust system.
Diesel engines provide significant fuel economy advantages at the expense of higher levels of regulated emissions. One of these diesel-produced emissions that must be regulated and controlled is commonly referred to as particulate matter.
Typically, the emission of particulate matter is significantly reduced by use of a diesel particulate filter (xe2x80x9cDPFxe2x80x9d). These filters are typically and operatively disposed within a vehicle""s exhaust system and are effective to catch and store particulate matter before it is released into the atmosphere. A vehicle""s DPF must be periodically regenerated as it becomes filled in order to dispose of the stored particulate matter. This regeneration is typically achieved by raising the temperature of the DPF to a predetermined level, and ensuring that the exhaust gas entering the DPF is of a certain composition.
Since the DPF is operatively placed within the exhaust system, the DPF increases the flow resistance and back pressure in the exhaust system as it becomes filled. In order to measure DPF loading and determine when a DPF should be regenerated, conventional systems monitor the pressure across the DPF (e.g., by the use of one or more pressure sensors disposed in the exhaust system) and the temperature of the DPF. These conventional systems combine these pressure and temperature measurements with engine operating data to arrive at a metric representative of DPF loading. The engine control unit monitors the appropriate signals and computes the loading metric continuously. Once the metric exceeds a predetermined calibratable threshold, the engine control unit switches to a regeneration strategy. While these systems are effective to accurately monitor DPF loading, the pressure and temperature sensors required to obtain the DPF loading measurements are relatively expensive and undesirably increase the overall cost of the vehicle.
There is therefore a need for a new and improved system and method for monitoring DPF loading which accurately determines when a DPF should be regenerated without the use of pressure and/or temperature sensors in the exhaust system.
It is a first object of the invention to provide a system and method for monitoring the loading of a diesel particulate filter (xe2x80x9cDPFxe2x80x9d) which overcomes at least some of the previously delineated drawbacks of prior systems, assemblies and methodologies.
It is a second object of the invention to provide a system and method for monitoring the loading of a DPF which accurately determines when the DPF should be regenerated.
It is a third object of the invention to provide a system and method for monitoring the loading of a DPF which does not require the use of costly pressure and/or temperature sensors within the vehicle""s exhaust system.
According to a first aspect of the present invention, a system is provided for monitoring loading of a diesel particulate filter which is operatively disposed within a vehicle of the type including an engine having an intake manifold and a turbocharger. The system includes at least one first sensor which is effective to measure at least one operating attribute of the engine and to generate a first signal representing the measured operating attribute; a second sensor which is operatively disposed within the intake manifold and which is effective to measure a boost pressure within the intake manifold and to generate a second signal representing the measured pressure; and a controller which is communicatively coupled to the first and second sensors, and which receives the first and second signals, the controller being effective to compare the received second signal to a nominal pressure value which is selected based upon the first signal, and to determine the loading of the diesel particulate filter based upon the comparison.
According to a second aspect of the present invention, a method is provided for monitoring loading of a diesel particulate filter which is operatively disposed within a vehicle of the type including an engine having a variable geometry turbine which maintains boost pressure in a closed-loop fashion. The method includes the steps of measuring at least one operating attribute of the engine; measuring a control effort of the variable geometry turbine; determining a nominal control effort for the variable geometry turbine based upon the measured at least one operating attribute; and comparing the measured control effort to the nominal control effort, effective to determine whether the diesel particulate filter is substantially filled.
These and other features, aspects, and advantages of the invention will become apparent by reading the following specification and by reference to the following drawings.